Functional fluid compositions

ABSTRACT

The present invention relates to a functional fluid composition comprising a glycol as a base material and a diamine-based noise reducer. According to the present invention as such, the functional fluid composition comprising a glycol as a base material and a diamine-based noise reducer represented by chemical formula 1 has an excellent noise reducing effect. In addition, the functional fluid composition of the present invention has an excellent metal corrosion inhibiting effect even, by using a diamine-based compound as a noise reducer, when a metal corrosion inhibitor composed of a triazole-based compound without including an amine-based compound is used as a metal corrosion inhibitor.

TECHNICAL FIELD

The present invention relates to a functional fluid composition and,more specifically, to a functional fluid composition comprising a glycolas a base material and a diamine-based noise reducer.

BACKGROUND ART

The present invention relates to a functional fluid composition usefulas a brake fluid. As typical automotive brake fluids, type 3 (DOT-3)brake fluid employing only a glycol ether compound as a solvent and type4 (DOT-4) brake fluid having about 30-60 wt % of a boron ester compoundfurther added to the type 3 (DOT-3) brake fluid are mainly used. TheDOT-3 type brake fluid employs only a glycol ether compound, which is alow-molecular weight material, and thus the DOT-3 type brake fluid, whenused for a long period of time, absorbs moisture in the air to lower thewet boiling point thereof, thereby causing a vapor lock phenomenon, sothat there is a danger of causing a braking accident. Moreover, theDOT-3 type brake fluid has weak metal corrosion inhibiting ability overa long period of time. In addition, the DOT-4 type brake fluid employs aboron ester compound to increase the equilibrium reflux boiling pointand the wet boiling point thereof, and thus the DOT-4 type brake fluidhas a higher degree of safety compared with the DOT-3 type brake fluid.However, the DOT-4 type brake fluid has problems in that a boronester-based compound is brought into contact with moisture to causehydrolysis, so that boric acid is precipitated, causing thedeterioration in physical properties of the brake fluid and thegeneration of foreign materials.

Therefore, the DOT-4 type brake fluid is used while an amine orsilane-based type stabilizer is added to prevent the precipitation ofboric acid (Korean Patent Publication No. 10-2004-0023917). However, theaddition of such a stabilizer causes a significant increase in noisewhen a master cylinder in the brake apparatus is operated.

In addition, Japanese Patent Publication No. 2013-227380 discloses thata brake fluid containing a fluoride compound has a stick slip preventingeffect through the improvement of lubricability. However, a fluoridecompound having a lipophilic group is hard to mix with a glycol ethersolvent having hydrophilicity.

DETAILED DESCRIPTION OF THE INVENTION Technical Problem

The present inventors endeavored to develop a functional fluidcomposition, and as a result, the present inventors experimentallyconfirmed that a functional fluid composition comprising a diamine-basednoise reducer represented by chemical formula 1 below has an excellentmetal corrosion inhibiting effect as well as an excellent noise reducingeffect, and thus the present inventors completed the present invention.

Therefore, an aspect of the present invention is to provide a functionalfluid composition comprising a glycol as a base material, thecomposition comprising a diamine-based noise reducer represented bychemical formula 1 below:

wherein in chemical formula 1, X is an integer of 1 or greater; and Yand Z are 0 or an integer of 1 or greater, the weight average molecularweight of the compound represented by chemical formula 1 being 400 ormore.

Technical Solution

In accordance with an aspect of the present invention, there is provideda functional fluid composition comprising a glycol as a base material,the composition comprising a diamine-based noise reducer represented bychemical formula 1 below:

wherein in chemical formula 1, X is an integer of 1 or greater; and Yand Z are 0 or an integer of 1 or greater, the weight average molecularweight of the compound represented by chemical formula 1 being 400 ormore.

In the composition of the present invention, the glycol base materialincludes a glycol compound and a boric acid ester compound.

The glycol compound may be any one known in the art, but preferably, theglycol compound is selected from the group consisting of ethyleneglycol, diethylene glycol, triethylene glycol, propylene glycol,dipropylene glycol, butylene glycol, polyalkylene glycol, glycol ether,and mixtures thereof. More preferably, the glycol compound suitable forthe composition of the present invention is ethylene glycol, diethyleneglycol, propylene glycol, dipropylene glycol, polyalkylene glycol, orglycol ether.

The glycol ether may be any one known in the art, and preferably, theglycol ether is selected from the group consisting of ethylene glycolethyl ether, diethylene glycol ethyl ether, triethylene glycol ethylether, ethylene glycol methyl ether, diethylene glycol methyl ether,triethylene glycol methyl ether, polyethylene glycol methyl ether,ethylene glycol butyl ether, diethylene glycol butyl ether, triethyleneglycol butyl ether, polyethylene glycol butyl ether, dipropylene glycolmethyl ether, polypropylene glycol methyl ether, and mixtures thereof.More preferably, the glycol ether suitable for the composition of thepresent invention is ethylene glycol methyl ether, diethylene glycolmethyl ether, triethylene glycol methyl ether, polyethylene glycolmethyl ether, ethylene glycol butyl ether, diethylene glycol butylether, triethylene glycol butyl ether, or polyethylene glycol butylether, and most preferably, triethylene glycol monomethyl ether,polyethylene glycol monomethyl ether, or polyethylene glycol monobutylether.

The boric acid ester compound is used to prevent the drop of a boilingpoint due to moisture absorption, and the boric acid ester compound iscontained in a content range of 30-60 wt % relative to 100% of the totalweight of the functional fluid composition. Here, if the amount of theboric acid ester compound used is less than the above range, a desiredeffect cannot be achieved. If the amount thereof exceeds the range, theproduction cost may be increased and boric acid may be precipitated.

According to a most preferable embodiment of the present invention, theglycol base material used in the present invention is a mixture of apolyalkylene glycol, polyethylene glycol monomethyl ether, polyethyleneglycol monobutyl ether, triethylene glycol monomethyl ether and a boricacid ester compound.

In the composition of the present invention, the content of the glycolbase material comprising a glycol compound and a boric acid estercompound is preferably 20-99 wt %, more preferably 40-99 wt %, stillmore preferably 60-99 wt %, still more preferably 70-99 wt %, and mostpreferably 85-99 wt %, based on the total weight of the functional fluidcomposition.

In the composition of the present invention, the diamine-based noisereducer may be represented by chemical formula 1 below:

wherein in chemical formula 1, X is an integer of 1 or greater; and Yand Z each are independently 0 or an integer of 1 or greater, the weightaverage molecular weight of the compound represented by chemical formula1 being 400 or more.

The weight average molecular weight of the compound represented bychemical formula 1 is preferably equal to or more than 400 and equal toor less than 5000, and more preferably equal to or more than 600 andequal to or less than 5000.

Among different molecular weights (M) that may be included in thecompound represented by chemical formula 1 herein, a molecular weight(M_(i)) of the compound that is optionally selected therefrom may becalculated by equation 1 below:

M _(i)=[74+{58×(X+Z)}(44×Y)]  [Equation 1]

wherein in equation 1, X is an integer of 1 or greater and Y and Z eachare independently 0 or an integer of 1 or greater.

Meanwhile, the weight average molecular weight (Mw) of the compoundrepresented by chemical formula 1 may be calculated by equation 2 below:

$\begin{matrix}\frac{\sum{n_{i}M_{i}^{2}}}{\sum{n_{i}M_{i}}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

wherein in equation 2, n_(i) means the total number of compounds havingan optional molecular weight M_(i).

In the composition of the present invention, the diamine-based compoundrepresented by chemical formula 1 as a noise reducer may be contained ina content of preferably 0.05-5.0 wt %, more preferably 0.1-5.0 wt %, andmost preferably 0.2-5.0 wt % based on the total weight of the functionalfluid composition.

According to an embodiment of the present invention, a diamine-basedcompound represented by chemical formula 2 in which Y=0 or Z=0 inchemical formula 1 may be contained as a noise reducer.

wherein in chemical formula 2, X is an integer of 1 or greater, themolecular weight of the compound represented by chemical formula 2 being400 or more.

The weight average molecular weight of the compound represented bychemical formula 2 is preferably equal to or more than 400 and equal toor less than 5000, and more preferably equal to or more than 600 andequal to or less than 5000.

Among different molecular weights (M) that may be included in thecompound represented by chemical formula 2, a molecular weight (M_(i))of the compound that is optionally selected therefrom may be calculatedby equation 3 below:

M _(i)=[74+(58×X)]  [Equation 3]

wherein in equation 3, X is an integer of 1 or greater.

Meanwhile, the weight average molecular weight (Mw) of the compoundrepresented by chemical formula 2 may be calculated by equation 2 above.

According to another embodiment of the present invention, thecomposition of the present invention may contain at least one additiveof a metal corrosion inhibitor and an antioxidant.

The metal corrosion inhibitor may be any one known in the art, but thecorrosion inhibitor used in the present invention is a triazole-basedcompound, an amine-based compound, or a mixture thereof.

The triazole-based compound includes various triazoles known in the art,and may be selected from the group consisting of a triazole derivative,a benzotriazole derivative, and a tolutriazole derivative. Specificexamples of the benzotriazole derivative includeN,N-bis(2-ethylhexyl)-4-methyl-1H-benzotriazole-1-methylamine,N,N-bis(2-ethylhexyl)-5-methyl-1H-benzotriazole-1-methylamine,octyl-1H-benzotriazole, di-tertiary butylated 1H-benzotriazole,1H-1,2,3-triazole, 2H-1,2,3-triazole, 1H-1,2,4-triazole,4H-1,2,4-triazole, 1-(1′,2′-di-carboxyethyl)benzotriazole,2-(2′-hydroxy-5′-methylphenyl)benzotriazole, 1H-1,2,3-triazole,2H-1,2,3-triazole, 1H-1,2,4-triazole, 4H-1,2,4-triazole, benzotriazole,tolyltriazole, carboxybenzotriazole, 3-amino-1,2,4-triazole,chlorobenzotriazole, nitrobenzotriazole, aminobenzotriazole, cyclohexano[1,2-d] triazole, 4,5,6,7-tetrahydroxy-tolyltriazole,1-hydroxybenzotriazole, ethylbenzotriazole, naphthotriazole,1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole,1-[N,N-bis(2-ethylhexyl)aminomethyl]tolyltriazole,1-[N,N-bis(2-ethylhexyl)aminomethyl]carboxy benzotriazole,1-[N,N-bis(di-(ethanol)-aminomethyl]benzotriazole,1-[N,N-bis(di-(ethanol)-aminomethyl]tolyltriazole,1-[N,N-bis(di-(ethanol)-aminomethyl]carboxybenzotriazole,1-[N,N-bis(2-hydroxypropyl)aminomethyl]carboxybenzotriazole,1-[N,N-bis(1-butyl)aminomethyl]carboxybenzotriazole,1-[N,N-bis(1-octyl)aminomethyl]carboxybenzotriazole,1-(2′,3′-di-hydroxypropyl)benzotriazole,1-(2′,3′-di-carboxyethyl)benzotriazole,2-(2′-hydroxy-3′,5′-di-tert-butylphenyl)benzotriazole,2-(2′-hydroxy-3′,5′-di-tert-amylphenyl)benzotriazole,2-(2′-hydroxy-4′-octoxyphenyl)benzotriazole,2-(2′-hydroxy-5′-tert-butylphenyl)benzotriazole,1-hydroxybenzotriazole-6-carboxylic acid, 1-oleoylbenzotriazole,1,2,4-triazole-3-ol, 3-amino-5-phenyl-1,2,4-triazole,3-amino-5-heptyl-1,2,4-triazole,3-amino-5-(4-isopropyl-phenyl)-1,2,4-triazole,5-amino-3-mercapto-1,2,4-triazole,3-amino-5-(p.tert-butylphenyl)-1,2,4-triazole,5-amino-1,2,4-triazole-3-carboxylic acid, 1,2,4-triazole-3-carboxyamide,4-aminourazole, 1,2,4-triazole-5-one, and the like.

Preferably, the triazole-based compound includes at least one selectedfrom benzotriazole, mercaptobenzotriazole, tolyltriazole, octyltriazole,decyltriazole, dodecyltriazole, and the like. More preferably, thetriazole-based compound is a mixture of benzotriazole andmercaptobenzotriazole.

In the composition of the present invention, the content of the triazolecompound as a metal corrosion inhibitor is 0.1-10 wt %, more preferably0.5-5.0 wt %, and most preferably 0.5-3.0 wt %, based on the totalweight of the functional fluid composition.

The amine-based compound may be selected from the group consisting of analkanol amine, an alkyl amine and a cyclic amine. Specific examples ofthe alkanol amine compound include monomethanolamine, dimethanolamine,trimethanolamine, monoethanolamine, diethanolamine, triethanolamine,monopropanolamine, dipropanolamine, tripropanolamine,monoisopropanolamine, diisopropanolamine, and triisopropanolamine;

specific examples of the alkylamine compound include dibutyl amine,tributyl amine, dicyclohexyl amine, cyclohexyl amine and a salt thereof,piperazine, n-propylamine, isopropylamine, n-butylamine, isobutylamine,sec-butylamine, tert-butylamine, n-pentylamine, n-hexylamine,n-heptylamine, n-octylamine, 2-ethylhexylamine, n-nonylamine,n-decylamine, 2-propylheptyl amine, n-undecylamine, n-dodecylamine,n-tridecylamine, isotridecylamine, n-tetradecylamine, n-pentadecylamine,n-hexadecylamine, n-heptadecylamine, n-octadecylamine, n-nonadecylamine,n-eicosyl-amine, di-(n-hexyl)amine, di-(n-heptyl)amine,di-(n-octyl)amine, di-(2-ethylhexyl)amine, di-(n-nonyl)amine,di-(n-decyl)amine, di-(2-propylheptyl)amine, di-(n-undecyl)amine,di-(n-dodecyl)amine, di-(n-tridecyl)amine, di-(isotridecyl)amine,di-(n-tetradecyl)amine, di-(n-pentadecyl)amine, di-(n-hexadecyl)amine,di-(n-heptadecyl)amine, di-(n-octadecyl)-amine, di-(n-nonadecyl)amine,di-(n-eicosyl)amine, n-hexylmethylamine, n-heptyl-methylamine,n-octylmethylamine, (2-ethylhexyl)methylamine, n-nonylmethylamine,n-decylmethylamine, (2-propylheptyl)methylamine, n-undecylmethylamine,n-dodecyl-methylamine, n-tridecylmethylamine, isotridecylmethylamine,n-tetradecylmethylamine, n-pentadecylmethylamine,n-hexadecylmethylamine, n-heptadecylmethylamine,n-octa-decylmethylamine, n-nonadecylmethylamine, n-eicosylmethylamine,and the like; and examples of the cyclic amine compound includemorpholine and the like.

The amine-based compound may include, preferably at least one selectedfrom methyl amine, dibutyl amine, triethyl amine, triethanol amine,cyclohexyl amine, and the like, and may be more preferably a mixture ofcyclohexyl amine and dibutyl amine.

In the composition of the present invention, the content of theamine-based compound as a metal corrosion inhibitor is 0.1-10 wt %, morepreferably 0.5-5.0 wt %, and most preferably 0.5-3.0 wt %, based on thetotal weight of the functional fluid composition.

Meanwhile, if the content of the metal corrosion inhibitor is less, acorrosion inhibiting effect can be obtained, and if the content thereofis more, a great noise may be generated when a master cylinder isoperated in the brake system. As the metal corrosion inhibitor, 0.1-1.5wt % of a triazole-based compound and 0.5-2.5 wt % of an amine-basedcompound based on the total weight of the functional fluid compositionmay be used in a mixture.

In addition, the diamine-based noise reducer represented by chemicalformula 1 described above exhibits an excellent metal corrosioninhibiting effect as well as an excellent noise reducing effect, andthus the metal corrosion inhibitor contained in the functional fluidcomposition of the present invention may be composed of only atriazole-based compound without including an amine-based compound. Incases where the metal corrosion inhibitor is composed of only atriazole-based compound, the content of the triazole compound as a metalcorrosion inhibitor is 0.1-10 wt %, more preferably 0.5-5.0 wt %, andmost preferably 0.5-3.0 wt % based on the total weight of the functionalfluid composition.

According to one embodiment of the present invention, in the functionalfluid composition, the metal corrosion inhibitor is a triazole-basedmetal corrosion inhibitor and does not comprise an amine-based metalcorrosion inhibitor.

In the composition of the present invention, the antioxidant is used forthe purpose of preventing oxidation, and may be any one known in theart, such as phenol-, amine-, sulfur-, and phosphorous-basedantioxidants. Specific examples of the phenol-based antioxidant include2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-p-cresol,2,6-di-tertiary-butyl-4-sect-butyl phenol, bisphenol A,di-butylhydroxyanisole, 4,4′-butylidenebis-(6-t-butyl-3-methylphenol),dibutylhydroxytoluene, and the like, and trimethyl dihydroquinoline orthe like may be used as a quinoline antioxidant.

Preferably, 3,5-di(tert-butyl)-4-hydroxytoluene (BHT) or the like may beused. The antioxidant may be contained in a content of 0.1-2.0 wt %relative to the total weight of the functional fluid composition. If thecontent of the antioxidant is less, an antioxidative effect cannot beobtained, and if the content thereof is more, a great noise may begenerated when a master cylinder is operated in the brake system.

Advantageous Effects

Features and advantages of the present invention are summarized asfollows.

(a) The present invention provides a functional fluid composition havinga glycol as a base material, the composition containing a diamine-basednoise reducer represented by chemical formula 1 below:

wherein in chemical formula 1, X is an integer of 1 or greater; and Yand Z are 0 or an integer of 1 or greater, the weight average molecularweight of the compound represented by chemical formula 1 being 400 ormore.

(b) The present invention may contain, as a noise reducer, adiamine-based compound represented by chemical formula 2 below in whichY=0 and Z=0 in chemical formula 1:

wherein in chemical formula 2, X is an integer of 1 or greater, theweight average molecular weight of the compound represented by chemicalformula 2 being 400 or more.

(c) The functional fluid composition of the present invention can havean excellent noise reducing effect by using a diamine-based compound asa noise reducer. In addition, the functional fluid composition of thepresent invention can exhibit an excellent metal corrosion inhibitingeffect even when a metal corrosion inhibitor composed of atriazole-based compound without including an amine-based compound isused.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows images illustrating a structure of a noise test device.

FIG. 2 shows the analysis of a sound waveform and a sound pressure level(dB) of the noise in examples and test example 1.

FIG. 3 shows the analysis of a sound waveform and a sound pressure level(dB) of a noise in examples and test example 2.

FIG. 4 shows the analysis of a sound waveform and a sound pressure level(dB) of a noise in examples and test example 3.

FIG. 5 shows the analysis of a sound waveform and a sound pressure level(dB) of a noise in examples and test example 4.

FIG. 6 shows the analysis of a sound waveform and a sound pressure level(dB) of a noise in examples and test example 5.

FIG. 7 shows the analysis of a sound waveform and a sound pressure level(dB) of a noise in examples and test example 6.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail withreference to examples. These examples are only for illustrating thepresent invention more specifically, and it will be apparent to thoseskilled in the art that the scope of the present invention is notlimited by these examples.

Examples and Test Example 1

(1) Preparation of Functional Fluid Composition

Functional fluid compositions of examples 1-1 to 1-5 and comparativeexamples 1-1 to 1-4 were prepared by using ingredients and compositionalratios thereof shown in table 1-1.

TABLE 1-1 Composition Example 1-1 Example 1-2 Example 1-3 Example 1-4Example 1-5 Polyalkylene glycol 5 5 5 5 5 Polyethylene glycol 14 14 1414 14 monomethylether Polyethylene glycol 13 13 13 13 13 monobutyletherTriethylene glycol 11.05 11 9.1 6.1 4.1 monomethylether Boric acid estercompound 53.4 53.4 53.4 53.4 53.4 Benzotriazole 0.5 0.5 0.5 0.5 0.5Mercapto benzotriazole 0.4 0.4 0.4 0.4 0.4 BHT 0.5 0.5 0.5 0.5 0.5Cyclohexylamine 0.6 0.6 0.6 0.6 0.6 Dibutylamine 1.5 1.5 1.5 1.5 1.5Diamine-based noise reducer 0.05 0.1 0.2 2 5 Comparative ComparativeComparative Comparative Composition example 1-1 example 1-2 example 1-3example 1-4 Polyalkylene glycol 5 5 5 5 Polyethylene glycol 14 14 14 14monomethylether Polyethylene glycol 13 13 13 13 monobutyletherTriethylene glycol 11.1 8.2 13.2 14.6 monomethylether Boric acid estercompound 53.4 53.4 53.4 53.4 Benzotriazole 0.5 0.5 0.5 Mercaptobenzotriazole 0.4 0.4 0.4 BHT 0.5 0.5 0.5 Cyclohexylamine 0.6Dibutylamine 1.5 Diamine-based noise reducer 2

Meanwhile, the diamine-based noise reducer employed a diamine-basedcompound represented by chemical formula 2 below and having a molecularweight of 230 Mw.

(2) Noise Test and Metal Corrosion Test

For a noise test, a noise test device shown in FIG. 1 was manufactured,and the noise level was evaluated while a brake pedal was repeatedlyoperated/returned.

The noise test device shown in the images of FIG. 1 is composed of: abooster unit which generates braking force by an operation of a brakepedal provided at one side of a vehicle driver seat; a master cylinderwhich receives the amplified force from the booster unit to generate abrake hydraulic pressure; wheel cylinders that are respectivelyinstalled on front and rear wheels to brake a car by the brake hydraulicpressure generated in the master cylinder; and an oil storage tank whichsupplies a brake fluid to the master cylinder and stores a brake fluidreturned from the wheel cylinders. Meanwhile, the brake fluid means afunctional fluid composition.

The noise test device was used to measure the level of noise, and thelevel of noise was scored according to the evaluation criteria in Table1-2 below. The results are shown in Table 1-3. In addition, the soundwaveform and sound pressure level (dB) of a noise were analyzed (soundanalysis program, WaveLab), and the results are shown in FIG. 2.

Meanwhile, the metal corrosion was evaluated according to the testmethod of paragraph 5.5 of KS M 2141 and the results are shown in Table1-3.

TABLE 1-2 Evaluation score Noise intensity ⊚ No noise ◯ Fine recognitionΔ Recognizable X Unsatisfactory

TABLE 1-3 Example Example Example Example 1-1 1-2 1-3 1-4 Example 1-5Noise X X X Δ Δ Metal Good Good Good Good Good corrosion ComparativeComparative Comparative Comparative example 1-1 example 1-2 example 1-3example 1-4 Noise X Δ X ⊚ Metal Good Good Cast iron Steel, corrosioncorrosion cast iron corrosion

Examples and Test Example 2

(1) Preparation of Functional Fluid Composition

Functional fluid compositions of examples 2-1 to 2-5 and comparativeexamples 2-1 to 2-4 were prepared by using ingredients and compositionalratios thereof shown in table 2-1.

TABLE 2-1 Composition Example 2-1 Example 2-2 Example 2-3 Example 2-4Example 2-5 Polyalkylene glycol 5 5 5 5 5 Polyethylene glycol 14 14 1414 14 monomethylether Polyethylene glycol monobutylether 13 13 13 13 13Triethylene glycol monomethylether 11.05 11 9.1 6.1 4.1 Boric acid estercompound 53.4 53.4 53.4 53.4 53.4 Benzotriazole 0.5 0.5 0.5 0.5 0.5Mercapto benzotriazole 0.4 0.4 0.4 0.4 0.4 BHT 0.5 0.5 0.5 0.5 0.5Cyclohexylamine 0.6 0.6 0.6 0.6 0.6 Dibutylamine 1.5 1.5 1.5 1.5 1.5Diamine-based noise reducer 0.05 0.1 0.2 2 5 Comparative ComparativeComparative Comparative Composition example 2-1 example 2-2 example 2-3example 2-4 Polyalkylene glycol 5 5 5 5 Polyethylene glycol 14 14 14 14monomethylether Polyethylene glycol monobutylether 13 13 13 13Triethylene glycol monomethylether 11.1 8.2 13.2 14.6 Boric acid estercompound 53.4 53.4 53.4 53.4 Benzotriazole 0.5 0.5 0.5 Mercaptobenzotriazole 0.4 0.4 0.4 BHT 0.5 0.5 0.5 Cyclohexylamine 0.6Dibutylamine 1.5 Diamine-based noise reducer 2

Meanwhile, the diamine-based noise reducer employed a diamine-basedcompound represented by chemical formula 2 below and having a molecularweight of 400 Mw.

(2) Noise Test and Metal Corrosion Test

The noise test and the metal corrosion test were carried out by the samemethod and criteria as in examples and test example 1. The results areshown in Table 2-2. Meanwhile, the sound waveform and sound pressurelevel (dB) of a noise were analyzed (sound analysis program, WaveLab),and the results are shown in FIG. 3.

TABLE 2-2 Example Example Example Example 2-1 2-2 2-3 2-4 Example 2-5Noise Δ Δ Δ Δ ◯ Metal Good Good Good Good Good corrosion ComparativeComparative Comparative Comparative example 2-1 example 2-2 example 2-3example 2-4 Noise X Δ X ⊚ Metal Good Good Cast iron Steel, corrosioncorrosion cast iron corrosion

Examples and Test Example 3

(1) Preparation of Functional Fluid Composition

Functional fluid compositions of examples 3-1 to 3-5 and comparativeexamples 3-1 to 3-4 were prepared by using ingredients and compositionalratios thereof shown in table 3-1.

TABLE 3-1 Composition Example 3-1 Example 3-2 Example 3-3 Example 3-4Example 3-5 Polyalkylene glycol 5 5 5 5 5 Polyethylene glycol 14 14 1414 14 monomethylether Polyethylene glycol monobutylether 13 13 13 13 13Triethylene glycol monomethylether 11.05 11 9.1 6.1 4.1 Boric acid estercompound 53.4 53.4 53.4 53.4 53.4 Benzotriazole 0.5 0.5 0.5 0.5 0.5Mercapto benzotriazole 0.4 0.4 0.4 0.4 0.4 BHT 0.5 0.5 0.5 0.5 0.5Cyclohexylamine 0.6 0.6 0.6 0.6 0.6 Dibutylamine 1.5 1.5 1.5 1.5 1.5Diamine-based noise reducer 0.05 0.1 0.2 2 5 Comparative ComparativeComparative Comparative Composition example 3-1 example 3-2 example 3-3example 3-4 Polyalkylene glycol 5 5 5 5 Polyethylene glycol 14 14 14 14monomethylether Polyethylene glycol monobutylether 13 13 13 13Triethylene glycol monomethylether 11.1 8.2 13.2 14.6 Boric acid estercompound 53.4 53.4 53.4 53.4 Benzotriazole 0.5 0.5 0.5 Mercaptobenzotriazole 0.4 0.4 0.4 BHT 0.5 0.5 0.5 Cyclohexylamine 0.6Dibutylamine 1.5 Diamine-based noise reducer 2

Meanwhile, the diamine-based noise reducer employed a diamine-basedcompound represented by chemical formula 2 below and having a molecularweight of 2000 Mw.

(2) Noise Test and Metal Corrosion Test

The noise test and the metal corrosion test were carried out by the samemethod and criteria as in examples and test example 1. The results areshown in Table 3-2. Meanwhile, the sound waveform and sound pressurelevel (decibel, dB) of a noise were analyzed (sound analysis program,WaveLab), and the results are shown in FIG. 4.

TABLE 3-2 Example Example Example Example 3-1 3-2 3-3 3-4 Example 3-5Noise Δ ◯ ⊚ ⊚ ⊚ Metal Good Good Good Good Good corrosion ComparativeComparative Comparative Comparative example 3-1 example 3-2 example 3-3example 3-4 Noise X ⊚ X ⊚ Metal Good Good Cast iron Steel, corrosioncorrosion cast iron corrosion

Examples and Test Example 4

(1) Preparation of Functional Fluid Composition

Functional fluid compositions of examples 4-1 to 4-5 and comparativeexamples 4-1 to 4-4 were prepared by using ingredients and compositionalratios thereof shown in table 4-1.

TABLE 4-1 Exam- Exam- Exam- Exam- Exam- Composition ple 4-1 ple 4-2 ple4-3 ple 4-4 ple 4-5 Polyalkylene glycol 5 5 5 5 5 Polyethylene glycol 1414 14 14 14 monomethylether Polyethylene glycol 13 13 13 13 13monobutylether Triethylene glycol 11.05 11 9.1 6.1 4.1 monomethyletherBoric acid ester 53.4 53.4 53.4 53.4 53.4 compound Benzotriazole 0.5 0.50.5 0.5 0.5 Mercapto benzotriazole 0.4 0.4 0.4 0.4 0.4 BHT 0.5 0.5 0.50.5 0.5 Cyclohexylamine 0.6 0.6 0.6 0.6 0.6 Dibutylamine 1.5 1.5 1.5 1.51.5 Diamine-based noise 0.05 0.1 0.2 2 5 reducer Compar- Compar- Compar-Compar- ative ative ative ative example example example exampleComposition 4-1 4-2 4-3 4-4 Polyalkylene glycol 5 5 5 5 Polyethyleneglycol 14 14 14 14 monomethylether Polyethylene glycol 13 13 13 13monobutylether Triethylene glycol 11.1 8.2 13.2 14.6 monomethyletherBoric acid ester 53.4 53.4 53.4 53.4 compound Benzotriazole 0.5 0.5 0.5Mercapto benzotriazole 0.4 0.4 0.4 BHT 0.5 0.5 0.5 Cyclohexylamine 0.6Dibutylamine 1.5 Diamine-based noise 2 reducer

Meanwhile, the diamine-based noise reducer employed a diamine-basedcompound represented by chemical formula 2 below and having a molecularweight of 4000 Mw.

(2) Noise Test and Metal Corrosion Test

The noise test and the metal corrosion test were carried out by the samemethod and criteria as in examples and test example 1. The results areshown in Table 4-2. Meanwhile, the sound waveform and sound pressurelevel (dB) of a noise were analyzed (sound analysis program, WaveLab),and the results are shown in FIG. 5.

TABLE 4-2 Example Example Example Example 4-1 4-2 4-3 4-4 Example 4-5Noise Δ ◯ ⊚ ⊚ ⊚ Metal Good Good Good Good Good corrosion ComparativeComparative Comparative Comparative example 4-1 example 4-2 example 4-3example 4-4 Noise X ⊚ X ⊚ Metal Good Good Cast iron Steel, corrosioncorrosion cast iron corrosion

Examples and Test Example 5

(1) Preparation of Functional Fluid Composition

Functional fluid compositions of examples 5-1 to 5-5 and comparativeexamples 5-1 to 5-4 were prepared by using ingredients and compositionalratios thereof shown in table 5-1.

TABLE 5-1 Exam- Exam- Exam- Exam- Exam- Composition ple 5-1 ple 5-2 ple5-3 ple 5-4 ple 5-5 Polyalkylene glycol 5 5 5 5 5 Polyethylene glycol 1414 14 14 14 monomethylether Polyethylene glycol 13 13 13 13 13monobutylether Triethylene glycol 11.05 11 9.1 6.1 4.1 monomethyletherBoric acid ester 53.4 53.4 53.4 53.4 53.4 compound Benzotriazole 0.5 0.50.5 0.5 0.5 Mercapto benzotriazole 0.4 0.4 0.4 0.4 0.4 BHT 0.5 0.5 0.50.5 0.5 Cyclohexylamine 0.6 0.6 0.6 0.6 0.6 Dibutylamine 1.5 1.5 1.5 1.51.5 Diamine-based noise 0.05 0.1 0.2 2 5 reducer Compar- Compar- Compar-Compar- ative ative ative ative example example example exampleComposition 5-1 5-2 5-3 5-4 Polyalkylene glycol 5 5 5 5 Polyethyleneglycol 14 14 14 14 monomethylether Polyethylene glycol 13 13 13 13monobutylether Triethylene glycol 11.1 8.2 13.2 14.6 monomethyletherBoric acid ester 53.4 53.4 53.4 53.4 compound Benzotriazole 0.5 0.5 0.5Mercapto benzotriazole 0.4 0.4 0.4 BHT 0.5 0.5 0.5 Cyclohexylamine 0.6Dibutylamine 1.5 Diamine-based noise 2 reducer

Meanwhile, the diamine-based noise reducer employed a diamine-basedcompound represented by chemical formula 1 below and having a molecularweight of 600 Mw.

(2) Noise Test and Metal Corrosion Test

The noise test and the metal corrosion test were carried out by the samemethod and criteria as in examples and test example 1. The results areshown in Table 5-2. Meanwhile, the sound waveform and sound pressurelevel (dB) of a noise were analyzed (sound analysis program, WaveLab),and the results are shown in FIG. 6.

TABLE 5-2 Example Example Example Example 5-1 5-2 5-3 5-4 Example 5-5Noise Δ ◯ ⊚ ⊚ ⊚ Metal Good Good Good Good Good corrosion ComparativeComparative Comparative Comparative example 5-1 example 5-2 example 5-3example 5-4 Noise X ⊚ X ⊚ Metal Good Good Cast iron Steel, corrosioncorrosion cast iron corrosion

Example and Test Example 6

(1) Preparation of Functional Fluid Composition

Functional fluid compositions of examples 6-1 to 6-5 and comparativeexamples 6-1 to 6-4 were prepared by using ingredients and compositionalratios thereof shown in table 6-1.

TABLE 6-1 Exam- Exam- Exam- Exam- Exam- Composition ple 6-1 ple 6-2 ple6-3 ple 6-4 ple 6-5 Polyalkylene glycol 5 5 5 5 5 Polyethylene glycol 1414 14 14 14 monomethylether Polyethylene glycol 13 13 13 13 13monobutylether Triethylene glycol 11.05 11 9.1 6.1 4.1 monomethyletherBoric acid ester 53.4 53.4 53.4 53.4 53.4 compound Benzotriazole 0.5 0.50.5 0.5 0.5 Mercapto benzotriazole 0.4 0.4 0.4 0.4 0.4 BHT 0.5 0.5 0.50.5 0.5 Cyclohexylamine 0.6 0.6 0.6 0.6 0.6 Dibutylamine 1.5 1.5 1.5 1.51.5 Diamine-based noise 0.05 0.1 0.2 2 5 reducer Compar- Compar- Compar-Compar- ative ative ative ative example example example exampleComposition 6-1 6-2 6-3 6-4 Polyalkylene glycol 5 5 5 5 Polyethyleneglycol 14 14 14 14 monomethylether Polyethylene glycol 13 13 13 13monobutylether Triethylene glycol 11.1 8.2 13.2 14.6 monomethyletherBoric acid ester 53.4 53.4 53.4 53.4 compound Benzotriazole 0.5 0.5 0.5Mercapto benzotriazole 0.4 0.4 0.4 BHT 0.5 0.5 0.5 Cyclohexylamine 0.6Dibutylamine 1.5 Diamine-based noise 2 reducer

Meanwhile, the diamine-based noise reducer employed a diamine-basedcompound represented by chemical formula 1 below and having a molecularweight of 900 Mw.

(2) Noise Test and Metal Corrosion Test

The noise test and the metal corrosion test were carried out by the samemethod and criteria as in examples and test example 1. The results areshown in Table 6-2. Meanwhile, the sound waveform and sound pressurelevel (dB) of a noise were analyzed (sound analysis program, WaveLab),and the results are shown in FIG. 7.

TABLE 6-2 Example Example Example Example 6-1 6-2 6-3 6-4 Example 6-5Noise Δ ◯ ⊚ ⊚ ⊚ Metal Good Good Good Good Good corrosion ComparativeComparative Comparative Comparative example 6-1 example 6-2 example 6-3example 6-4 Noise X ⊚ X ⊚ Metal Good Good Cast iron Steel, corrosioncorrosion cast iron corrosion

For reference, the method for evaluating metal corrosion according tothe test method of paragraph 5.5 of KS M 2141 is as follows.

(1) Corrosion Test Method

Metal test pieces (tinned iron, steel, aluminum, cast iron, brass,copper) polished with 320A silicon carbide to avoid surface impressionswere prepared with a surface area of 25.5 cm². The respective metalpieces were weighed to 0.1 mg, and then were brought into electriccontact with each other through bolt assembling.

The assembled metal pieces and a standard SBR cup were placed in a 475ml-volume glass bottle, and a brake fluid mixed with 5 vol % ofdistilled water was allowed to fill 400 ml. The glass bottle was tightlyclosed with a tin-plated iron lid having a ventilation hole (0.8±0.1) mmin diameter, and then placed in an oven at 100±2° C. for 120±2 hours.

The bottle was cooled at room temperature for 60-90 minutes, and thenthe metal pieces were immediately taken out, washed water, and thenwiped with a cloth wetted with 95% ethanol one by one. The metal pieceswere inspected for corrosion or impression marks.

Meanwhile, the metal test pieces and the brake fluid test cup used inthe corrosion test are shown in tables 7 and 8 below.

TABLE 7 Metal test pieces listed in Annex B of KS M 2141 Copper plateMaterial General material Surface corrosion standard data DimensionThickness requirements Tinned ASTM A-624 Tinplate, Electrolytic As Assheared. iron Fed. Spec. bright sr type Mr. T-3 purchased Clean anduniform QQ-T-425A No. 2885 IB tinning Steel SAE 1018 Low carbon sheet,≈0.2 cm Edge machined to Cold rolled remove shearing Hardness 40HB-72HBmarks, clean uniform surfaces Aluminum SAE AA 2024 Wrought aluminum ≈0.2cm Edge machined to alloy, temper T-3, remove shearing hardness: 75Bmarks, clean typical uniform surfaces Cast iron SAE G 3000 automotivecast Length ≈ 8 cm ≈0.4 cm Surface grind iron. Shall be free Width ≈ 1.3cm sides to from shrinkage Surface area ≈ dimension using cavities,porosity or (25 ± 2) cm² well-dressed No. any other defects 80 alundumdetrimental to wheel, clean specification use of uniform surfaces thematerial. Hardness: 86HB-98HB Brass SAE CA 260 wrought alloy- ≈0.2 cmEdge machined to yellow brass rolled remove shearing sheet or piece,marks, clean Hardness: 54HB-74HB uniform surfaces Copper SAE CA 114Cold-rolled copper ≈0.2 cm Edge machined to sheet or piece, removeshearing Hardness: 35HB-56HB marks, clean uniform surfaces Note: Drillhole with 4 mm-5 mm in diameter and aapprox. 6 mm from one end of eachpiece. Holes shall be clean and free from burrs. Hardness range arecommercial for the designated metals. Hardness is not specified for thetinned iron because it is not considered a practical rerquirement. Testpieces (strips) can be obtained from Society of Automotive EngineersInc., 400 Commonwalth Drive, Warrendale, Pa. 15096, USA or Laboratoirede Recherches et de controle du caoutchouc, 12 rue Crves, 9212Dmontrouge, France.

TABLE 8 Brake fluid test cup defined in annex A of KS M 2141 IngredientWeight ratio SBR 1503^(a) form 100 Oil furnace black (NBS 378) 40 Zincoxide (NBS 370) 5 Sulfur (NBS 371) 0.25 Stearic acid (NBS 372) 1N-tertiary-butyl-2-benzothiazole sulphenamide (NBS 384) 1Symmetrical-dibetanaphthyl-p-phenylenediamine 1.5 Dicumyl peroxide (40%on precipitated CaCO₃)^(b) 4.5 Total 153.25 Note: The ingredient list(NBS . . . ) should have the same technical characteristics as onesprovided by the National Bureau of Standards (U.S.A.). ^(a)Philprene1503 is suitable. ^(b)used within 90 days after preparation and storedat a temperature of 27° C. or less.

(2) Corrosion Evaluation Method

When the brake fluid was tested according to the corrosion test method,the weights of the test pieces were measured by the unit of 0.1 mg, andthe variation (mg/cm²) was calculated according to the equation 4.

The weight change should not exhibit the corrosion exceeding thereference values shown in Table 9 below. The outer contact surface ofthe metal piece should not be impressed or roughened enough to bevisible to the naked eye. However, the metal piece was allowed to bestained or decolorized.

The brake fluid/water mixture should not be hardened at (23±5°) C. atthe end of the test, and the formed crystalline precipitates should notstick to the wall of the glass bottle or the surface of the metal piece.The mixture should not contain 0.1 vol % or more of precipitate, and thepH of the mixture should be equal to or higher than 7.0 and equal to orlower than 11.5.

$\begin{matrix}{{Variation} = \frac{{{weight}\mspace{14mu} {before}\mspace{14mu} {test}} - {{weight}\mspace{14mu} {after}\mspace{14mu} {test}}}{{surface}\mspace{14mu} {area}}} & \left\lbrack {{Equation}\mspace{14mu} 4} \right\rbrack\end{matrix}$

TABLE 9 Maximum allowable weight change Test piece (mg/cm², surfacearea) Tinned iron 0.20 Steel 0.20 Aluminum 0.10 Cast iron 0.20 Brass0.40 copper 0.40

1. A functional fluid composition comprising a glycol as a basematerial, the composition comprising a diamine-based noise reducerrepresented by chemical formula 1 below:

wherein in chemical formula 1, X is an integer of 1 or greater; and Yand Z are 0 or an integer of 1 or greater, the weight average molecularweight of the compound represented by chemical formula 1 being 400 ormore.
 2. The functional fluid composition of claim 1, wherein the weightaverage molecular weight of the compound represented by chemical formula1 is equal to or more than 400 and equal to or less than
 5000. 3. Thefunctional fluid composition of claim 1, wherein the weight averagemolecular weight of the compound represented by chemical formula 1 isequal to or more than 600 and equal to or less than
 5000. 4. Thefunctional fluid composition of claim 1, wherein the diamine-based noisereducer of chemical formula 1 is comprised in a content of 0.05-5.0 wt %based on the total weight of the functional fluid composition.
 5. Thefunctional fluid composition of claim 1, wherein the diamine-based noisereducer of chemical formula 1 is comprised in a content of 0.1-5.0 wt %based on the total weight of the functional fluid composition.
 6. Thefunctional fluid composition of claim 1, wherein the diamine-based noisereducer of chemical formula 1 is comprised in a content of 0.2-5.0 wt %based on the total weight of the functional fluid composition.
 7. Thefunctional fluid composition of claim 1, wherein the composition furthercomprises at least one additive selected from a group consisting of ametal corrosion inhibitor and an antioxidant.
 8. The functional fluidcomposition of claim 7, wherein the metal corrosion inhibitor is atriazole-based metal corrosion inhibitor and does not comprise anamine-based metal corrosion inhibitor.
 9. The functional fluidcomposition of claim 1, wherein in chemical formula 1, Y=0 and Z=0, theaverage molecular weight of the compound represented by chemical formula1 being 400 or more.
 10. The functional fluid composition of claim 9,wherein the weight average molecular weight is equal to or more than 400and equal to or less than
 5000. 11. The functional fluid composition ofclaim 9, wherein the weight average molecular weight is equal to or morethan 600 and equal to or less than
 5000. 12. The functional fluidcomposition of claim 9, wherein the diamine-based noise reducer ofchemical formula 1 is comprised in a content of 0.05-5.0 wt % based onthe total weight of the functional fluid composition.
 13. The functionalfluid composition of claim 9, wherein the diamine-based noise reducer ofchemical formula 1 is comprised in a content of 0.1-5.0 wt % based onthe total weight of the functional fluid composition.
 14. The functionalfluid composition of claim 9, wherein the diamine-based noise reducer ofchemical formula 1 is comprised in a content of 0.2-5.0 wt % based onthe total weight of the functional fluid composition.
 15. The functionalfluid composition of claim 9, wherein the composition further comprisesat least one additive selected from a group consisting of a metalcorrosion inhibitor and an antioxidant.
 16. The functional fluidcomposition of claim 15, wherein the metal corrosion inhibitor is atriazole-based metal corrosion inhibitor and does not comprise anamine-based metal corrosion inhibitor.